Replacing Shifter Cable Housing

[capezio11]

Someone gave me a Schwinn Aluminum 564 road bike. I decided to start commuting to work on it and I took it for a test run of my route on Saturday. I haven't owned a bike since I was a teen so innacuracies may abound in this post.
When I got home I noticed that the shifter cable housing right next to the rear hub/derailer had exploded. I remember trying to shift into the lowest gear and it was not wanting to shift easily, but I forced it a little and it went into gear. At the time I thought nothing of the resistance, figuring the bike had not been riden in ten years and it was in need of a tune-up.
Now I need to repair the cable housing (glad I found this site for that) but I am wondering if the demise of the shifter cable housing is indicative of a more substantial problem?

[DaveM]

It probably happened just because the plastic of the housing had dried out and weakened. So not a big issue. But the fact you had to "force" it into the lowest gear does indicate that your derailleur and/or shifter are not adjusted correctly. Check the limit screws on the derailleur and tension on the cable. Also be on the look out if the derailleur was bent at some point. This is not too unusual. The damage to the housing could have been from a minor impact.